It is well known that a double glazed window is very advantageous for its efficient thermal insulation. This is a result of the two glass panels trapping an air layer therebetween. Of course, it is necessary that the double glazed window unit be thoroughly sealed, else said unit would lose its particular insulating properties.
Louver blinds are often used with window structures for be positioned anywhere between a first and a second position that respectively allow most of the light to come through the window or block most of it, louver blinds being relatively aesthetic and inexpensive.
It is known in the art to incorporate a louver blind structure into a double glazed window unit, the slats of the louver blind being positioned between the two glass panels. The slats still allow an air layer to exist between the glass panels, and therefore the window unit does not lose its insulating properties, unless it is not properly sealed. One of the main advantages with this structure is that both slats and window form a single integral structure, and consequently simplifies the handling of the structure.
U.S. Pat. No. 3,702,040 issued in 1972 to the applicant Fernand ROY (hereafter the '040 patent) shows a typical louver blind structure for a double glazed sealed window unit. The window unit 1 comprises a peripheral frame 3, 4 spacing the glass panels 2 in a parallel relationship and a plurality of stud shafts 10, 11, axially aligned in pairs, that are engaged by and support the slats 9 in a parallel fashion. On one side of the window unit, inside the frame, the stud shafts have an enlarged diameter 19 and have outwardly protruding pins 20 that are inserted into complementary openings 21 inside an elongated vertical actuator bar 22. If actuator bar 22 is lifted or lowered, it will rotate pins 20 which will cause the reciprocating movement of stud shafts 10, 11 and slats 9. This will allow the user to position slats 9 as desired, i.e. anywhere between a closed overlapping position wherein the louver blind structure blocks most of the light and an opened spaced position wherein the louver blind structure allows most of the light to pass through. An outer gear wheel 42 allows an operator to lift or lower the actuator bar, and thus to simultaneously pivot the slats at the desired angle.
There are three main problems related to such structures. The first problem is that the drive mechanism, e.g. manually actuated wheel 42 in the '040 patent, is positioned outside the window unit. It therefore requires space to be installed around the window, e.g. a hole fitted in the wall adjacent to the window for the casing of the wheel. This is not desirable, since the conventional window openings cannot be used without modifications to accommodate such a window and louver blind assembly, complicating the installation of the assembly significantly. The second problem is that, due to the moving parts that link the drive mechanism with the actuating mechanism, it is difficult if not impossible to perfectly seal the window unit. The double glazed window unit therefore loses a fraction of its efficiency because of this leak in its insulation. The third problem is related to the fact that it is very complicated to reach the louver blind structure once the window unit is sealed and installed. However, the problem only comes up if it is necessary to reach the louver blind structure: some parts, such as moving parts, are prone to breaking, and in the known art, these moving parts are not installed very securely. Indeed, the driving shaft, linking the power means (the manually operated gear wheels 40 to 42 in the '040 patent) to the actuating means (the actuator bar 22 in the '040 patent), will be prone to loosen its engagement with the actuating means since it is supported at its two extremities by two moving parts, namely the power means and the actuator means. If there is to be a problem with the louver blind structure, it becomes very expensive to repair them.